President Donald Trump’s bid to exclude undocumented immigrants from a census tabulation used to determine how many U.S. representatives are apportioned to each state is unworkable and unconstitutional, according to civil rights groups and several American cities and counties suing the administration.

“It can’t be done,” Sarah Brannon, managing attorney with the American Civil Liberties Union’s Voting Rights Project, told VOA, adding that the citizenship determination Trump is mandating would be hard to ascertain and “not very reliable.”

Experts Say Collecting Immigration Data Through US Census for Reapportionment Is Unconstitutional

Another civil liberties group, Common Cause, filed a lawsuit Thursday challenging Trump’s directive, joined by cities in New Jersey and Georgia. Later in the day, Arlington County, Virginia, said it was joining the suit.

Experts Say Collecting Immigration Data Through US Census for Reapportionment Is Unconstitutional

“The Constitution requires an accurate count of our population every 10 years,” Arlington County Board Chair Libby Garvey said in a statement. “We must have an accurate count of everyone living in Arlington and refuse to allow this unlawful effort to scare people and suppress the census count of our immigrant community.”

Experts Say Collecting Immigration Data Through US Census for Reapportionment Is Unconstitutional

Others are applauding the executive order. Alabama’s Attorney General Steve Marshall called it a “victory” for the state.

“When the states’ congressional seats and Electoral College votes are divided up, representation should be based on those people who reside in their states and this country lawfully,” .

The Supreme Court last year blocked the Trump administration from including a citizenship question on the 2020 census.

In an executive order issued earlier this week, Trump directed Commerce Secretary Wilbur Ross, who oversees the U.S. Census Bureau, to present data as to the number of undocumented people counted by the census. The administration would then exclude the undocumented from each state’s census count for the purpose of determining whether a state loses, gains or retains members in the House of Representatives, a process that occurs every 10 years.

reads: “For the purpose of the reapportionment of Representatives following the 2020 census, it is the policy of the United States to exclude from the apportionment base aliens who are not in a lawful immigration status under the Immigration and Nationality Act.”

The U.S. Constitution makes no mention of citizenship in relation to the census or congressional apportionment, a point underscored by law professor Ilya Somin, who teaches at George Mason University in Virginia.

“Section 2 of the 14th amendment specifically says that representatives shall be apportioned among the several states according to their respective numbers, counting the whole number of persons in each state,” Somin, a self-described libertarian, told VOA. “I think the overwhelming likelihood is the courts will rule against [Trump’s directive] because it is blatantly unconstitutional.”

On Tuesday, the Trump administration argued the Constitution “does not specifically define which persons must be included for the purposes of apportionment and requires only that representatives be apportioned according to what has long been understood to mean the ‘inhabitants’ of each state.”

But Howard University Constitutional Law Professor Steven Jamar told VOA the argument the administration is using deals with a subset of people – such as tourists and business travelers – who, though they might be counted in the census, are not counted for apportionment purposes.

“There are some people who are not within the state on the date of the census. They are traveling or they're out of the country. … There are some people who are just tourists visiting the state from somewhere else. And those people have historically not been counted for apportionment purposes. … they’re generally not even counted in the census because they aren't resident in the state. But an immigrant, whether they're documented or not, is residing in the state,” Jamar said.

Trump, however, vowed to “collect all of the information we need to conduct an accurate census and to make responsible decisions about public policy, voting rights, and representation in Congress.”

Last year the Supreme Court blocked an attempt by the Trump administration to add a citizenship question for the first time in 60 years.

“It's not about who can vote. It’s not about citizenship. It's about whole persons residing in the state. So, the question is really just ‘Who's living there?’” Jamar said.

The Heritage Foundation, a conservative think tank based in Washington, agrees with the administration’s directive, adding that Trump acted “firmly within his statutory authority to determine who are the ‘inhabitants’ of a state for purposes of apportionment.”